1. Field of the Invention
The present invention relates to a conditional access system such as a conditional access cable television system. In particular, the invention relates to identification of packages of bundled services, called entitlement units, and the authorization of reception of an entire entitlement unit.
2. Description of Related Art
Known conditional access systems individually authorize each service to be received. For example, a subscriber of a cable television system may subscribe to a plurality of services (e.g., HBO, Cinemax, ShowTime, etc.).
Known conditional access systems provide services to subscribers in tiers. Tiers are used as a way to provide standard service to some subscribers while providing premium services to other subscribers. Each subscriber is assigned to a specific tier. For example, consider a service that provides two tiers: a standard service that carries over the air broadcast programs and a premium service that carries the standard service plus HBO, Cinemax and ShowTime. Tier authorization data is transmitted from the system's headend to a home communication terminal for each subscriber where it is stored. In this example, the tier authorization data may be a single bit set to indicate premium service and cleared to indicate standard service. In general, many tiers (e.g., 256) may be provided. The tier authorization data may be a number (e.g., from 0 to 255) that indicates the authorized tier. Each tier corresponds to a specific combination of authorized programs out of a list of available programs (e.g., out of 128 available programs). Alternatively, the tier authorization data may be a long data word (e.g., 128 bits or 16 bytes of 8 bit each) where each bit in the tier authorization data corresponds to an authorized program. The tier authorization data in this example is merely the long data word with as many bits set as there are authorized programs for the tier, and the identification of the authorized programs is by noticing the bit position that is set.
No matter how the tier authorization data is encoded, it is transmitted from the headend to a subscriber's home communication terminal. Each subscriber is authorized for a particular tier. A table that relates the tier authorization data for each subscriber to the correspondingly identified home communication terminal is stored in the headend. For each subscriber, the headend prepares a unique addressed message containing the tier authorization data corresponding to the subscriber, and the headend transmits the data to the subscriber's home communication terminal. Often the data is encrypted by the headend and decrypted by the home communication terminal.
Programs broadcast from the headend are identified by frequency, channel number, digital data stream number, etc. The home communications terminal processes a subscriber's request for a particular program by determining a number associated with the requested program and verifying that the terminal is authorized to receive a tier that “contains” the program.